Various machinery exists for dispensing and spreading bulk fertilizer material, generally organic fertilizers such as manure, over an agricultural field. In many commercial farming operations, organic material, including fertilizers such as animal manure, are stored in a holding area. The manure is at some point taken up and placed in a spreader of some sort and dispensed onto fields when desired. As a result of the great variety of materials used in agriculture and the differences in terrain, climate and culture, a variety of material spreaders have been developed over the years.
Box spreaders, as the name implies, include a wheeled box-like container having one or more generally horizontal screws aligned parallel with the direction of travel of the box spreader and running along the length of the bottom of the box spreader from front to back. As the screws turn the helical threads move the material towards a rear opening in the box spreader and out through the opening where the material is generally broken up and spread outwardly by rotating beaters, often referred to as expellers. Due to the discharge openings being located generally along a bottom rear portion of the box spreader, such spreaders are best employed with relatively dry materials, as any liquids would tend to leak out through the openings.
In order to accommodate materials having a higher liquid content, including slurries, sealed containers have been developed for preventing unwanted discharge of the material. Typical of these are tank spreaders including one or more generally horizontal augers for moving the material through the tank.
The present invention relates more particularly to material spreaders for drier materials, such as cattle manure. In addition to the augers which move the material through the spreader to a discharge opening in one end, these spreaders include a material expeller which disperses the material outwardly over the ground passing beneath the spreader. These material spreaders are generally some variation of either a rotating screw or a number of paddles affixed to an axle, with the screws and axles conventionally being mounted horizontally and being positioned below the floor line of the container. The paddles are rigidly secured to the screw or axle and extend out and around the axle in a helical shape. Material is drawn out of the spreader as the axle spins with the rigid paddles being highly susceptible to rock damage resulting in poorer distribution of material and higher costs for repair and replacement of paddles along the axle.
In addition to distributing the material over the ground surface, it is advantageous for the material spreader to break up the larger clumps of material. The more effectively the material is broken up and thrown to a distance away from the material spreader, the more uniform the coverage of the ground surface. Most known rotating systems of paddles or screws do not always provide an optimal level of material consistency and uniformity of dispersal where the throw acceleration is limited to the torsional speed of rotation of the screw or axel. Conventional spreaders also commonly use a hydraulic push assembly to force material into the screw expeller resulting in compression of the material and inconsistent field distribution patterns. Accordingly, there is a need for a material expeller for a material spreader resulting in improved material consistency and uniformity of dispersal.